Answer:
she walked 6 miles.
Step-by-step explanation:
We know that Ruth walks at a speed of 4 mph and it took her 1.5 hours to walk from her home to the library (from 9 to 10.30).
We can solve this using a rule of three:
If she walks 4 miles in 1 hour, how many hours did she walk in 1.5 hours?
1 hour 4 miles
1.5 hours x miles
Solving for x we get:
miles
Thus, she walked a distance of 6 miles
Answer:
Step-by-step explanation:
A solid straight line has a positive slope and goes through (0, negative 1) and (3, 0)
<em>Find the slope of the solid line</em>
The equation of the solid line in slope intercept form is equal to
we have
---> given problem
substitute
Everything above and to the left of the line is shaded
so the inequality is equal to
Answer:
about 50 percent of its former width.
Step-by-step explanation:
Let's assume that our parameter of interest is given by and in order to construct a confidence interval we can use the following formula:
Where is an estimator for the parameter of interest and the margin of error is defined usually if the distribution for the parameter is normal as:
Where is a quantile from the normal standard distribution that accumulates
of the area on each tail of the distribution. And
represent the standard error for the parameter.
If our parameter of interest is the population proportion the standard of error is given by:
And if our parameter of interest is the sample mean the standard error is given by:
As we can see the standard error for both cases assuming that the other things remain the same are function of n the sample size and we can write this as:
And since the margin of error is a multiple of the standard error we have that
Now if we find the width for a confidence interval we got this:
And we can express this as:
And we can define the function since as we can see the margin of error and the standard error are function of the inverse square root of n. So then we have this:
The subscript i is in order to say that is with the sample size n
If we increase the sample size from n to 4n now our width is:
The subscript f is in order to say that is the width for the sample size 4n.
So then as we can see the width for the sample size of 4n is the half of the wisth for the width obtained with the sample size of n. So then the best option for this case is:
about 50 percent of its former width.